Electromagnet.



PATENTED SEPT. 1, 1903.

J. DUNCAN. ELECTROMAGNET. APPLICATION FILED JUNE 1. 1903.

N0 MODEL.

NI/ENTOR.

UNITED STATES y Patented September. 1, 1903.

PATENT OFFICE.

JAMES DUNCAN, OF BOSTON, MASSACHUSETTS, ASSIGNOR TO AMERICAN TELEPHONE AND TELEGRAPH COMPANY, `A CORPORATION OF NEW YORK.

EILECTRONIAGNET.4

SPECIFICATION forming part of Letters Patent No. 737,720, dated September 1, 1903.

Application filed June 1.1903. Serial No. 159,663. (No model.)

To all whom, it may concern:

Be it known that I, JAMES DUNCAN, residing at Boston, in the county of Suffolk and State of Massachusetts, have invented certain Improvements in Electromagnets, of which the following is a specification.

It is well known that electromagnets are frequently composed of a metal core upon the ends of which are snugly-fitting disks of some insulating material, such as hard rubber or some insulating fiber, the space between the disks being filled with several layers of ne insulated wire wound tightly over each other. The core, with the disks, constitute what is commonly called the spool, and terminal means are provided in one disk, to which the inner and outer ends of the windings of in sulated wire are led and attached usually by soldering and to which the external conductors are connected. The common terminal means for this purpose in electromagnets employed in connection with telephone-circuits is to insert two pins into one of the disks diametrically opposite to each other and parallel with the core, holes Vbeing bored through the disk and counterbored on the inner face of the disk to receive the pins. Nuts are placed in the counterbores on the inner ends of the pins, and other nuts upon the pins bear upon the outer face of the disk, which is thus held between them. The inner end of the coil-windings is led through a small inclined hole in the disk to its outer side and soldered to one of the pins, while the outer end of the windings may be led through a second holein the disk and soldered to the second pin. The principal objection to terminal connections of this character is that the nuts become loose, and the pin is then liable to be turned and break the wire of the winding at the pinor inside the disk and turned around and may be easily retightened without breaking the wire from the coil in any case.

In the drawings accompanying this specilication, Figures l and 2 are respectively end and side elevations of a magnet-spool provided with coil-winding terminals as devised by me. Fig. 3 is a view on line yy of Figli of the inner surface of the spool-disk to which the terminals are connected, and Fig. 4 is a section on line s s on Fig. 3. Figs. 5 and 6 are respectively side and edge views of the terminal clip detached, and Figs. 7, 8, and 9 are sections on line w w on Fig. 3 to illustrate the method of inserting and securing the terminal clip in place in the head or disk of the spool.

To obviate the various defects heretofore referred to, I have devised the invention disclosed in the accompanying drawings, where- B represents the spool of an electromagnet, consisting of a suitable metal core b, having the heads or disks a a2 secured at each end, the core ends extending beyond the disks a proper distance. one of the heads or disks a of the electromagnet B, I forrn two parallel depressions or channels i c', one on each side of the core ZJ, and

Anear the periphery of the disk of a suitable width and depth and at right angles to the channels and central with the disk are cut the two radial slits 7c lo, oneextending across each channel. An inclined hole g is drilled in the disk in the usual manner, through whichthe inner end of the coil-winding is threaded.

Figs. 5 and 6 show a clip m, made from thin narrow sheet metal bent upon itself, having a T-shaped upset end 2, with a long single extension l and a shorter extension 3, laid close to and double with the part 1. This constitutes the terminal to whichthe ends of the coil-windings are soldered, as I will now proceed to describe. To attach the clip m to either side of the disk 0., its extension l is held outside and above the slit 7o and the doubled part is passed down as far as it can go and then drawn forward, so that the head 2 will come into the channel t', as shown in Fig. 7. Then the short extension 3 is bent Across the inner face of IOO over onto the outer face of the disk, as shown in Fig. 8, and firmly pressed down. This secures the clip on its short-extension side. Then a pair of pincers is placed upon the long extension close down to the face of the disk and the said extension given a one-quarter turn in either direction, which makes a lock or obstruction 5, which secures the clip on the long-extension side. The clip is held from turning about, as the head lits closely in the channel and its extensionsll the slit tightly, and it cannot be forced inward or become loosened endwise because it is held to the disk on one side by a projection from the head and the bent-over part 3 and on the other side by the other head projection and the obstruction 5, produced by the twist givento the part 1, so that there can be no loosening of the terminal from any ordinary cause. As represented in Fig. 2, the ends of v the coil-windings w 102 are soldered to the respective clips m m, the inner end w passing through the hole g, while the outer end to2 may be brought through the slit. Should the portion p become softened from heat conducted thereto by the extension 1 and thereby loosen the clip, it can be tightened again by giving another twist to the extension, and if for any cause it becomes necessary to remove the clip this can be easily done by untwisting the extension, lifting up the part 3, and pushing the clip inward the thickness of its head and drawing it out from the slit k.

Having thus fully described the invention, I claim- 1. The combination in an electromagnet, of a core, a coil of wire, and a disk of insulating material on each end of the core, one of the disks having a radial slit from its periphery into an enlarged depression on the inner side thereof, with a metal terminal extending outward from said disk and provided with an enlarged head adapted to rest in said depression, with means integral with the terminal for holding its head in the depression, as set forth.

2. The combination in an electromagnet, of a core, a coil of wire, and an insulating-disk on each end of the core, one disk having a channel across its inner face bisected by a radial slit, with a terminal clip composed of a narrow metal strip bent upon itself into irregular lengths and its head upset, the head of the clip resting in said channel and its extensions in the slit, one of which is bent over onto the outer face of the disk, while the other is twisted around to form an obstruction, as set forth.

3. The combination in an electromagnet, of a core, a coil of wire, and an insulating-disk on each end of the core, one disk having two channels across its inner face on opposite sides thereof, each bisected by a radial slit, with terminal clips composed of a narrow metal strip bent upon itself into irregular lengths and its head upset, the head of each clip resting in its channel, both extensions passing through the slit, one being bent over onto the outer face of the disk and the other twisted around to form an obstruction, as set forth.

4. The combination in an electromagnet of a core, a coil of insulated wire, and a disk of insulating material on each end of the core, one disk having a channel across its inner face bisected by a radial slit, with a terminal clip composed of a narrow metal strip bent upon itself into irregular lengths and its head upset, the head of the clip resting in said channel, both extensions passing through the slit, one being bent over onto the outer face of the disk and the other twisted around to form an obstruction, theinner end of the coil extending through a hole into the disk and soldered to the twisted extension, as set forth.

5. The combination in an electromagnet, of a core, a coil of wire, and disks of insulating material on each end of the core, one disk having two channels across its inner face on opposite sides thereof each bisected by a radial slit, with terminal clips composed of a narrow metal strip bent upon itself into irregular lengths and its head upset, the head of each clip resting in its channel, both eX- tensions passing through the slit, one being bent over onto the outer face of the disk and the other twisted around to form an obstruction, the inner end of the coil extending through a hole into the disk, the outer end of the coil passing through the slit, and both ends of the coil soldered to their terminals, as set forth.

In testimony whereof I have signed my name to this specification, in the presence of two subscribing witnesses, this 26th day of May, 1903.

JAMES DUNCAN.

Witnesses:

GEo. WILLIS PIERCE, FRANK C. LooKwooD.

IOO 

